connect a analog input in differential connection

[alphones]

iam using three flowmeters and a pressure transducer and they are connected to PCI-MIO-16 E 1 DAQ card. i have connected all three in differential mode. i have connected them as channels 0 to 3.channel 0 AI0(+)AND ai8(-) and AI 8 to AIGND(67) for grounding.in the same way for other flowmeters i have grounded the -ve pin to AIGND.but i get incorrect values . can anyone help me in this issue?

[Wilfried_71]

You made a mistake : you don't have to connect DIRECTLY the aignd to the (-) pin (ai8 for example) :

- if your signal source is grounded, just connect your sensor to ai0 and ai8

- if your signal is floating, just connect the ai8 to aignd WITH a resistance from 100 kOhm up to 1MOhm.

You can see in the ni.com web site to obtain a connection diagram.

[alphones]

hi,

i have connected the sensor +ve to ai0 and -ve to ai8 and then i connected ai8 to aignd by another piece of wire for grounding . in the same way for channel 1 + to ai1 and - to ai9 and interconnected ai9 and aignd(32) and for pressure transducer + to ai2 , - to ai10 and directly  connected the ground wire from transducer to aignd(64) and for channel 3 + to ai3 and - to ai11 and interconnected ai11 and aignd(29).this is the way i did.still i have problem. can u help me and give me the link where i can find the connection diagram for my DAQ card.

[Speedy_Badger]

Hello alphones,

Wilfried brought up some good questions to ask. Are your sensors grounded or floating? In either case his descriptions are accurate as to how you will need to connect the sensors to your device. I have linked the connection diagram for the PCI-MIO-16E along with a really great wiring guide. Let me know if you have any additional questions.

E Series User Manual (Appendix B, figure B-1)
Field Wiring and Noise Considerations for Analog Signals (Table 1 has a lot of great information)

Regards,